<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Title</title>
</head>
<body>
<div>
  <input type="text" placeholder="请输入一个整数" v-model="num1">
  <input type="text" placeholder="请输入一个整数" v-model="num2">
  <input type="button" value="加" @click="f('+')">
  <input type="button" value="减" @click="f('-')">
  <input type="button" value="乘" @click="f('*')">
  <input type="button" value="除" @click="f('/')">
  <h1>结果:{{info}}</h1>
</div>

<script src="js/vue.min.js"></script>
<script>
  let v = new Vue({
    el: "body>div",
    data: {
      num1: "",
      num2: "",
      info: ""
    },
    methods: {
      f(flag) {
        if (isNaN(v.num1) || isNaN(v.num2)) {
          v.info = '输入的不是数字,请重新输入';
          return;
        }
        v.info = eval(v.num1 + flag + v.num2)
      }
    }
  })
</script>
</body>
</html>